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Title: Exclusion of EEG-based arousals in wake epochs of polysomnography leads to underestimation of the arousal index.
Austin Authors: Wilson, Danielle L ;Tolson, Julie ;Churchward, Thomas J ;Melehan, Kerri;O'Donoghue, Fergal J ;Ruehland, Warren R 
Affiliation: Respiratory and Sleep Medicine
Institute for Breathing and Sleep
Royal Prince Alfred Hospital, Sydney, Australia
Faculty of Medicine, University of Melbourne, Melbourne, Australia
Faculty of Medicine and Health, University of Sydney, Sydney, Australia
Issue Date: 1-May-2022
Publication information: Journal of Clinical Sleep Medicine 2022; 18(5): 1385-1393
Abstract: There is an internal contradiction in current American Academy of Sleep Medicine standards for arousal index (AI) calculation in polysomnography: Arousals in sleep and wake epochs are counted, but only sleep time is used in the denominator. This study aimed to investigate the impact of including arousals scored in wake epochs on the AI. We compared AIs including (AIinc) vs excluding (AIexc) awake-epoch arousals from 100 consecutive polysomnograms conducted for investigation of possible obstructive sleep apnea. To determine the AI that most closely approximated "truth," AIinc and AIexc were compared to an AI calculated from continuous sleep analysis (AIcont) in a 20-polysomnogram subgroup of patients. The median (interquartile range) increase in AIinc was 5.2 events/h (3.5-8.1) vs AIexc (AIinc = 28.0 events/h [18.4-38.9] vs AIexc = 22.9 events/ h [13.1-31.3]), equating to an increase of 25.3% (15.6-40.8). As the AI increased, the difference increased (P < .001), with decreasing sleep efficiency and an increasing apnea-hypopnea index as the strongest predictors of the difference between AIexc and AIinc. The absolute AIexc-AIcont difference (7.7 events/h [5.1-13.6]) was significantly greater than the AIinc-AIcont difference (1.2 events/h [0.6-5.7]; z = -3.099; P = .002). There was a notable increase in AI when we included wake-epoch arousals, particularly in patients with more severe obstructive sleep apnea or reduced sleep efficiency. However, the AI including wake-epoch arousals best matched the "true" continuous sleep-scoring AI. Our study informs clinical and research practice, highlights epoch scoring pitfalls, and supports the current American Academy of Sleep Medicine standard arousal reporting approach for future standards. Wilson DL, Tolson J, Churchward TJ, Melehan K, O'Donoghue FJ, Ruehland WR. Exclusion of EEG-based arousals in wake epochs of polysomnography leads to underestimation of the arousal index. J Clin Sleep Med. 2022;18(5):1385-1393.
DOI: 10.5664/jcsm.9878
ORCID: 0000-0001-6754-7359
Journal: Journal of Clinical Sleep Medicine : JCSM : Official Publication of the American Academy of Sleep Medicine
PubMed URL: 35022129
PubMed URL:
Type: Journal Article
Subjects: analysis
Appears in Collections:Journal articles

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